Our research projects
Tree lines and climate: the impact of climate change on tree line altitudes in Fennoscandia
People involved: PhD candidate Jasmine Byrne (USN), Professor emeritus Arvid Odland (USN), Professor Dieu Tien Bui (USN), Dr Roland Pape (USN), Professor Hans Renssen (USN) and Kick Sprenger (Aeres University of Applied Sciences)
Themes: Climate, Vegetation
Alpine tree lines represent an important ecological boundary, separating the boreal forest belt from the treeless alpine tundra. The altitude of alpine tree lines depends on many different local factors, such as the involved tree species, exposition of the terrain, slope angle, substrate, the size of the mountain range and climatic conditions. Despite all these different factors, it has been proposed that the worldwide undisturbed alpine tree lines follow a common climatic envelope. This suggests that the elevation of high elevation tree lines may be predicted using meteorological data alone. Based on this principle, a mathematical model has been constructed that successfully simulated the tree line positions at a continental to global scale. In Fennoscandia, tree line elevations vary greatly from 900 m in the south of Norway to sea level in the very north. Under the influence of global warming, it is anticipated that Fennoscandian tree lines will shift to higher elevations. This could potentially lead to a decrease in the future areal extent of vulnerable alpine ecosystems in Fennoscandia, and it is thus important to make a detailed quantitative analysis of the impact of future warming scenarios on local tree line altitudes. Therefore, this project aims to predict the change in alpine tree lines in Fennoscandia under influence of climate change.
Publication: Byrne, J., Renssen, H., Bui, D. T., & Odland, A. (2022). Assessment of the TREELIM model in predicting present treeline along a longitudinal continentality-maritimity gradient in south-western Norway. Geografiska Annaler: Series A, Physical Geography, 104(2), 90–108. https://doi.org/10.1080/04353676.2022.2054147
Climates of the past: modelling and characterization of climate, environment, and human impact during the past 150,000 years
People involved: Dr. Frank Arthur (USN, now at University of Leeds), Professor Hans Renssen (USN), Professor Didier M. Roche (Laboratoire des Sciences du Climat et de l’Environnement), Dr. Huan Li (Nantong University), Dr. Anhelina Zapolska (Vrije Universiteit Amsterdam), Dr. Yurui Zhang (Xiamen University)
Theme: Climate, Vegetation
Studying past climates is important for our understanding of climate variability. In the past 150,000 years, the climate shifted between relatively warm conditions during interglacials and very cold conditions during glacials. The past 150,000 years covers two interglacials, the Eemian (130 to 116 thousand years ago) and the Holocene (the last 11,5 thousand years). These two interglacials are separated by the last cold glacial era when most of Fennoscandia was covered by a big ice sheet. Traditionally there are two independent methods to study these past climates: 1) reconstructions of the climate based on geological and archeological archives, and 2) simulations using numerical models of climate. In our research, we apply both methods to study different aspects of climate, including transient changes in Europe during the Holocene and Eemian and the impact of climate change on vegetation during both interglacials.
Publications (past 5 years):
Arthur, F., Zapolska, A., Roche, D.M., Li, H., Renssen, H. Modelling the Climate of the Eemian in Europe Using an Interactive Physical Downscaling. Quaternary, under revision.
Arthur, F., Hatlestad, K., Lindholm, K.-J., Loftsgarden, K., Löwenborg, D., Solheim, S., Roche, D.M., Renssen, H. (2024) The impact of volcanism on Scandinavian climate and human societies during the Holocene: Insights into the Fimbulwinter eruptions (536/540 AD). The Holocene, doi:10.1177/09596836231225718.
Arthur, F., Roche, D.M., Fyfe, R., Quiquet, A., Renssen, H. (2023) Simulations of the Holocene climate in Europe using an interactive downscaling within the iLOVECLIM model (version 1.1). Climate of the Past 19, 87-106, doi: 10.5194/cp-19-87-2023.
Cruz-Silva, E., Harrison, S.P., Prentice, I.C., Marinova, E., Bartlein, P.J., Renssen, H., Zhang, Y. (2023) Pollen-based reconstructions of Holocene climate trends in the eastern Mediterranean region. Climate of the Past 19, 2093-2108, doi: 10.5194/cp-19-2093-2023.
Li, H., Renssen, H., Roche, D.M. (2022) Comparison of the green-to-desert Sahara transitions between the Holocene and the last interglacial. Climate of the Past 18, 2303-2319, doi: 10.5194/cp-18-2303-2022.
Renssen, H. (2022) Climate model experiments on the 4.2 ka event: the impact of tropical SST anomalies and desertification, The Holocene 32 (5), 378-389, doi: 10.1177/09596836221074031.
Renssen, H., Roche, D.M. (2024) Arctic sea‐ice export as a mechanism for cold climate events during the last deglaciation. Journal of Quaternary Science, doi: 10.1002/jqs.3665.
Zapolska, A., Serge, M.A., Mazier, F., Quiquet, A., Renssen, H., Vrac, M., Fyfe, R., Roche, D.M. (2023) More than agriculture: Analysing time-cumulative human impact on European land-cover of second half of the Holocene. Quaternary Science Reviews 314, doi: 10.1016/j.quascirev.2023.108227.
Zapolska, A., Vrac, M., Quiquet, A., Extier, Th., Arthur, F., Renssen, H., Roche, D.M. (2023) Improving biome and climate modelling for a set of past climate conditions: evaluating bias correction using the CDF-t approach. Environmental Research: Climate (2) 025004, doi: 10.1088/2752-5295/accbe2
Zhang, Y., Renssen, H., Seppä, H., Li, Z., Li., X. (2025) A stretched polar vortex increased mid-latitude climate variability during the Last Glacial Maximum. Climate of the Past 21, 67-77, doi:10.5194/cp-21-67-2025.
Zhao, W., Li, H., Chen, C., Renssen, H. (2022) Large-scale vegetation response to the 8.2 ka BP cooling event in East Asia. Palaeogeography, Palaeoclimatology, Palaeoecology 608, 111303, doi: 10.1016/j.palaeo.2022.111303
